A BD FACSAria TM desktop cell sorter is being requested in this shared instrumentation proposal. It will be installed in an existing core facility that serves more than 40 investigators, who collectively have 49 NIH grants, in addition to support from NSF and private agencies. A very highly trained technician efficiently operates a Cytomation MoFIo cell sorter in this facility. However, the instrument is over-booked and cannot be used with less than two weeks advanced notice. Also, the complexity of the MoFIo is such that it cannot be operated by less skilled personnel. In contrast, the FACSAria is user friendly, does not require daily calibration and has nearly the same capability for high speed, high purity sorts. Moreover, it occupies a fraction of the space and utilizes low maintenance, air-cooled lasers. Therefore, this instrument will more than double our capacity for cell sorting, removing a very serious limitation to progress in many NIH supported projects. In addition, it will allow the facility to better serve our community by encouraging new research applications that depend on cell sorting. Management procedures for sorting will continue as before, but we will be able to resume training activities that were suspended for lack of capacity. Relevant data will be archived and transferred to investigators as is currently done with the existing cell sorter and two flow cytometers. All of these instruments will continue to be well maintained under full service contracts.